Image Arithmetics and Combining
Image Arithmetics (|imarith|)
Image Combining (|imcombine|)
Combining images is performed in astropop using the |imcombine| function. It is designed to combine FrameData using several methods and rejection algorithms.
The current combine methods are:
- median
- average
- sum
The current rejection methods are:
- minmax_clip
- sigma_clip
Math Details
Sum Combine
Sigma Clipping
To perform sigma clipping, it is recomended to use median as central tendency and mad_std as deviation estimation. These two estimators handle outliers better then the mean and standard deviation of the distribution, so produce much better results in sigma clipping. A detailed analysis can be found on the CCD Data Reduction Guide.